Rheumatoid arthritis-associated antibodies in healthy first-degree relatives of RA patients.

Rheumatoid arthritis (RA) affects approximately 1.5% of the population worldwide and 0.5-3.3% of the Mexican population. The presence of rheumatoid factor (RF), anti-citrullinated protein antibodies (ACPA) and anti-carbamylated protein (anti-CarP) antibodies has been described in populations at risk of RA development, such as first-degree relatives (FDR). Anti-CarP antibodies are present in RA patients (44%), FDR of RA patients (18%) and healthy controls (4.7%). Anti-CarP antibodies have not been described in FDR of the Mexican population. The objective of this study was to determine the prevalence of Rheumatoid Factors (RF) isotypes, ACPA and anti-CarP antibodies isotypes in FDR of RA patients. An observational, cross-sectional study, in an FDR of RA cohort, was performed. We measured IgA, IgG and IgM isotypes of RF, ACPA and anti-CarP antibodies. A total of 144 FDRs from 99 RA patients were enrolled. The prevalence of anti-CarP antibodies was 2.8% for IgA, 4.2% for IgG, whereas IgM was not detected. The serologic association was for RF/ACPA 4.48%, RF/anti-CarP 2.7%, FR 64.5%, ACPA 1.3%, ACPA/anti-CarP 0.69%, anti-CarP 3.4%, and no RF/ACPA/anti-CarP was observed. We found a low prevalence of anti-CarP antibodies in our cohort of FDR of RA patients, but the prevalence of ACPA and RF were higher than other cohorts previously reported.

Anti-carbamylated protein antibodies positivity and disease activity in Hispanic patients with established rheumatoid arthritis: An observational study.

OBJECTIVES: We aimed to determine the prevalence of anti-carbamylated protein (anti-CarP) antibodies in Mexican Hispanics with established rheumatoid arthritis (RA) and to assess their relationship with disease activity. METHODS: A cohort study was conducted in 278 patients with established RA during an 18-month follow-up. We measured IgG/IgM/IgA rheumatoid factor (RF), IgG anticitrullinated protein antibodies (ACPA) and IgG/IgM/IgA anti-CarP antibodies using enzyme-linked immunosorbent assay (ELISA). For disease activity, we performed the 28-joint disease activity score with erythrocyte sedimentation rate (DAS28-ESR). Repeated measures one-way ANOVA was used to test the association between anti-CarP IgG antibody status and longitudinal DAS28-ESR scores. Patients were evaluated at baseline and at 6, 12, and 18 months during follow-up. RESULTS: Anti-CarP IgG antibodies were positive in 47.8% of patients and, accounting for all isotypes, in 9.5% of patients with negative RF and ACPA. Triple antibody positivity was present in 42.6% of patients in our sample. Anti-CarP IgG antibody positivity did not show statistically significant differences in mean DAS28-ESR when compared to anti-CarP IgG antibody negative patients at baseline, 6, 12 or 18 months. CONCLUSION: Anti-CarP IgG antibodies are not associated to a higher disease activity in Hispanic patients with established RA. Our findings suggest that the clinical value of measuring anti-CarP antibodies in RA diminishes over time.